DeepSeek Harness before 0.1.2-alpha.1 has an auth bypass in the local HTTP control-plane API: the server trusts a spoofed Host header instead of the real TCP origin. Remote attackers can call privileged endpoints like commands/execute with danger-full-access, relax session approval to unconfined execution, and dump stored conversations without credentials. Upgrade to 0.1.2-alpha.1 or later to mitigate.